Designing of rpd

DESIGNING OF REMOVABLE
PARTIAL DENTURES
Dr. Paavana
II MDS

CONTENTS
• INTRODUCTION
• TERMINOLOGIES
• BASIC PRINCIPLES OF RPD CONSTRUCTION
• BIOMECHANICS AND DESIGN SOLUTIONS
• POSSIBLE MOVEMENTS OF PARTIAL DENTURE
• FACTORS INFLUENCING MAGNITUDE OF STRESS
TRANSMITTED TO THE ABUTMENT TEETH

• DIFFERENCES IN PROSTHESIS SUPPORT AND THE INFLUENCE
ON DESIGN
• CONTROLLING STRESS BY DESIGN CONSIDERATIONS
• PHILOSOPHY OF DESIGN
 STRESS EQUALISATION
 PHYSIOLOGIC BASING
 BROAD STRESS DISTRIBUTION
• DESIGN PROCEDURE
• ESSENTIALS OF DESIGN
 CLASS I AND II
 CLASS III
 CLASS IV
• REVIEW OF LITERATURE
• CONCLUSION

INTRODUCTION
• The primary objective of partial denture design is the
preservation of the remaining teeth, their supporting
structures, the residual alveolar ridges and the oral mucosa in a
healthy condition, while at the same time replacing the missing
teeth for improving aesthetics, mastication and speech.
• Emphasis must thus be placed first on the biological
aspects of Partial Denture restorations, rather than upon the
purely technical aspects.

Great controversy continues to exist as to what
constitutes correct design and adequate support for
the removable partial dentures.
The method for using and equalizing support from the
edentulous ridge and remaining teeth remains the
main issue. The different methods used have given
rise to various design philosophies.

DESIGN: To plan and /or delineate by drawing the
outline of a proposed prosthesis.

SURVEYOR: A paralleling
instrument used in
construction of dental
prosthesis to locate and
delineate the contours and
relative positions of the
abutment teeth and
associated structures.
SURVEYING: An analysis and
comparison of the
prominence of intraoral
contours associated with the
fabrication of dental
prosthesis .

UNDERCUT: The portion of the
surface of an object that is
below the height of contour in
relationship to the path of
placement.
GUIDING PLANE:
vertically parallel surfaces on
abutment teeth and/or dental
implant abutments oriented so
as to contribute to the
direction of the path of
placement and removal of a
removable prosthesis

SURVEY LINE: Line produced on a cast by a surveyor
marking the greatest prominence of contour in
relation to the planned path of placement of a
restoration.

The PATH OF INSERTION is the direction in which a
restoration moves from the point of initial contact of
the rigid part with the supporting teeth to the
terminal resting position , with the rest seated and
the denture base in the contact with the tissues.
The PATH OF REMOVAL is the direction in which a
restoration moves from its terminal rest position to
the last contact of its rigid part with the supporting
teeth.

MAJOR CONNECTOR:
The part of a partial removable dental prosthesis that
joins the components on one side of the arch to those
on the opposite side
MINOR CONNECTOR:
the connecting link between the major connector or the
base of a partial removable dental prosthesis and
other units of the prosthesis, such as the clasp
assembly, indirect retainers, occlusal rests, or
cingulum rests

OCCLUSAL REST:
a rigid extension of a removable partial
dental prosthesis that contacts the
occlusal surface of a tooth or
restoration, the occlusal surface of
which may have been prepared to
receive it
DIRECT RETAINER:
That component of partial removable
dental prosthesis used to retain and
prevent dislodgement, consisting of a
clasp assembly or precision attachment

INDIRECT RETAINER:
That component of a partial
removable dental prosthesis
that assists the direct retainer
in preventing displacement of
the distal extension denture
base by functioning through
lever action on the opposite
side of the fulcrum line when
the denture base moves away
from the tissues in pure
rotation around the fulcrum
line

BASIC PRINCIPLES OF RPD
CONSTRUCTION
• First expounded by A H Schmidt in 1956
1. The dentist must have a thorough knowledge of
both the mechanical and biological factors involved
in RPD design
2. Treatment plan must be based on complete
examination and diagnosis of the individual patient

3. The dentist must correlate the pertinent factors and
determine a proper plan of treatment – he alone
can modify the conditions in the mouth to enhance
the success of the treatment
4. The RPD should restore the form and function
without injury to the remaining oral structure
5. “A removable partial denture is a form of treatment
and NOT a cure”

BIOMECHANICS AND DESIGN
SOLUTIONS

• Removable partial dentures by design are intended to
be placed into and removed from the mouth. As they
are not fixed to the tissues, they are subject to
movement in response to functional loads, such as
those created by mastication.
• Consideration of the forces inherent in the oral cavity
is critical. This includes the direction, duration,
frequency, and magnitude of the force

• If the potentially destructive forces can be minimized,
then the physiological tolerances of the supporting
structures are not exceeded and pathological change
does not occur.
• It is important for clinicians providing RPD service to
understand the possible movements in response to
function and to be able to logically design the
component parts of the removable partial denture to
help control these movements

• An understanding of simple machines applied to the
design of removable partial dentures helps to
accomplish the objective of preservation of oral
structures
• Machines can be classified as
Simple
Complex
• Simple machines include – lever, wedge, screw, wheel
and axle, inclined plane and pulley

LEVER
A Lever is a rigid bar
supported somewhere
along its length. It may
rest on the support, or
may be supported from
above. The support point
of the lever is called the
fulcrum, and the lever can
move around the fulcrum.

• FIRST CLASS LEVER: fulcrum is in center, resistance at one end,
and effort / force is at the opposite end. This is the most
efficient and easily controlled lever
• In dental terms, E- force of occlusion / gravity, F- tooth surface
such as an occlusal rest and R – resistance provided by a direct
retainer/guide plane surface

• SECOND CLASS LEVER: fulcrum is at one end, effort at
opposite end and resistance in center. This type is
seen as indirect retention in RPDs.

• THIRD CLASS LEVERS: fulcrum is at one end,
resistance at opposite, and effort in center. This class
is not commonly encountered in RPDs.

• INCLINED PLANE
Forces against the
inclined plane may
result in deflection of
that which is applying
the force or may result
in movement to the
inclined plane, neither
of these results are
desirable.
Inclined planes are not a
factor when the partial
denture is tooth
supported.

POSSIBLE MOVEMENTS OF PARTIAL
DENTURE
• Differences in displaceability of the periodontal
ligament of the supporting abutment teeth and soft
tissue covering the residual ridge permit this rotation.
The rotation of the prosthesis is in a combination of
directions rather than unidirectional. There are three
possible movements of the distal extension partial
dentures

The rotational movement of an extension base type removable
partial denture, when a force is placed on the denture base.

• SAGITTAL PLANE:
Rotation around the fulcrum
line passing through the
most posterior abutments
when the denture base
moves vertically toward or
away from the supporting
residual ridge
Rotational movement
around this fulcrum line or
axis is of the greatest
magnitude of that around
the three fulcrums but not
necessarily the most
damaging

• Movement of the base in the opposite direction is
resisted by the action of the retentive clasp arms on
terminal abutments and the action of stabilizing
minor connectors in conjunction with seated, vertical
support elements of the framework anterior to the
terminal abutments acting as indirect retainers.
• Indirect retainers should be placed as far as possible
from the distal extension base, affording the best
possible leverage against the lifting of the distal
extension base

• FRONTAL PLANE:
rotation around a longitudinal axis
formed by the crest of the ridge
it extends through the occlusal rest
on the terminal abutment and the
crest of the residual ridge on one
side of the arch.
In a class I situation there will be 2 of
these fulcrums, one on each side of
the arch. This fulcrum controls
rotational movements of the
denture- rocking, side- to- side
movements over the crest of the
ridge

• This type of movement is resisted primarily by the
rigidity of the major and minor connectors and their
ability to resist torque.
• If the connectors are not rigid, or if a stress breaker
exists between the distal extension base and the
major connector, this rotation about a longitudinal
axis either applies undue stress to the sides of the
supporting ridge or causes horizontal shifting of the
denture base.

• HORIZONTAL PLANE
Rotation around a vertical
axis located near the center
of the arch.
The fulcrum is located in the
vicinity of the midline just
lingual to to the anterior
teeth. This fulcrum line is
vertical, and it controls the
rotational movement of the
denture in the horizontal
plane or the flat circular
movements of the denture

• This type of movement occurs under function
because diagonal and horizontal occlusal forces are
brought to bear on the partial denture.
• It is resisted by stabilizing components, such as
reciprocal clasp arms and minor connectors that are
in contact with vertical tooth surfaces.
• Stabilizing components on one side of the arch act to
stabilize the partial denture against horizontal forces
applied from the opposite side.

• Horizontal forces always will exist to some degree
because of lateral stresses occurring during
mastication and bruxism.
• These forces are accentuated by the failure to
consider the orientation of the occlusal plane, the
influence of malpositioned teeth and effect of
abnormal jaw relationships.
• The amount of horizontal shift occurring in the partial
denture will therefore depend on the magnitude of
lateral forces applied and effectiveness of stabilizing
components.

• Since 3 movements are possible in a distal
extension partial denture, occlusal rest should
not have steep vertical walls or locking dove
tails, which could possibly cause horizontal and
torquing forces to be applied intracoronally to
the abutment teeth

FACTORS INFLUENCING
MAGNITUDE OF STRESSES
TRANSMITTED TO ABUTMENT
TEETH

• LENGTH OF SPAN:
• Longer the edentulous span, the longer will be the
denture base and greater will be the force
transmitted to the abutment teeth. The fulcrum is
located at or near the occlusal rest on the terminal
abutment tooth.

• When treatment is being planned, every effort
should be made to retain a posterior abutment tooth
to avoid a class I or class II situations.
•
A base that begins next to the cuspid will have a
greater degree of movement than will the one that
begins distal to the second bicuspid.

• QUALITY OF SUPPORT OF RIDGE:
The form of the residual ridge can play a large part in
dissipating forces created by function of the partial
denture. Large, well formed ridges are capable of
absorbing greater amounts of stress than are small,
thin, or knife-edged ridges.

• A healthy mucoperiosteum approximately 1mm thick
is capable of bearing a great functional load than is a
thin atropic mucosa.
• Soft, flabby, displaceable tissue contributes little to
the vertical support of the denture and nothing to the
lateral stability of the denture base. This type of tissue
allows excessive movement of the denture, with
resultant transmission of stress to the adjacent
abutment tooth.

• QUALITIES OF CLASPS
• The more flexible the retentive arm of the clasp, the
less stress is transmitted to the abutment tooth. This
is the reason the combination or wrought wire
retentive clasp was suggested for the terminal
abutments for class I or II partial dentures
• A flexible clasp arm contributes less resistance to the
more destructive horizontal stresses. Therefore, as
flexibility of the clasp increases, both the lateral and
vertical stresses transmitted to the residual ridge
increase.

• If the periodontal support of the abutment tooth is
good, a less flexible clasp such as a vertical projection
clasp would be indicated because the tooth would
more likely be able to withstand a greater amount of
stress.
• If, on the other hand, the periodontal support has
been weakened, a more flexible clasp such as the
combination clasp with a wrought wire retentive arm
should be used so that the residual ridge would share
more of the resistance to horizontal forces acting on
the partial denture

• CLASP DESIGN:
• A Clasp that is designed so that it is passive when it is
completely seated on the abutment tooth will exert
less stress on the tooth than one that is not passive.
Only when the frame work is completely seated, will
the retentive clasp arms be passive.
• A clasp should be designed so that during insertion or
removal of the prosthesis, the reciprocal arm contacts
the tooth before the retentive tip passes over the
greatest bulge of the abutment. This will stabilize /
neutralize the stress to which the abutment tooth is
subjected as the retentive terminal passes over the
greatest bulge of the tooth

LENGTH OF CLASP:
• The more flexible a clasp, the less stress it will exert
on the abutment tooth. Flexibility can be increased by
increasing the length of the clasp. Doubling the length
of the clasp will increase the flexibility five times.
Clasp length may be increased by using a curved rather
than a straight course on an abutment tooth

• MATERIAL USED IN CLASP CONSTRUCTION:
• A clasp constructed of chrome alloy will normally
exert greater stress on abutment tooth, than a gold
clasp, all other factors being equal, because of greater
rigidity of the chrome alloy. To compensate for this
property, clasp arms of chrome alloys are constructed
with a smaller diameter than a gold clasp would be to
accomplish the same purpose.

• ABUTMENT TOOTH SURFACE:
• The surface of a gold crown / restoration offers more
frictional resistance to clasp arm movement than
does the enamel surface of a tooth. Therefore,
greater stress is exerted on a tooth restored with gold
than on a tooth with intact enamel.

• OCCLUSAL HARMONY:
• A disharmonious occlusion generates horizontal forces that,
when magnified by the factors of leverage, can transmit
destructive forces to both the abutment teeth and the residual
ridges.
• The area of the denture base against which the occlusal load is
applied significantly influences the amount of stress
transmitted to the abutment teeth and ridge. If occlusal load is
applied to the base adjacent to the abutment tooth, there will
be less movement of the denture base and less stress
transmission than if the load is applied at the distal end of the
denture base

• Ideally, the occlusal load should be applied in the
center of the denture bearing area, both antero-
posteriorly and bucco-lingually. In most mouths, the
second premolar and first molar represent the best
areas for application of the masticating load. Artificial
teeth should be arranged so that the bulk of the
masticatory force is applied in that area

DIFFERENCES IN PROSTHESIS
SUPPORT AND THE INFLUENCE ON
DESIGN

• The methods adopted to control the movements of
the partial denture depends on whether the
prosthesis is tooth-supported or tooth-tissue
supported.
• For a tooth supported prosthesis, the movement
potential is less because teeth provide resistance to
functional loading. Teeth do not vary widely in ability
to provide this support; consequently, designs for
prostheses is less variable

• For tooth-tissue –supported prosthesis, the residual
ridge presents a quite variable potential for support.
• The underlying alveolar bone demonstrates a highly
variable form following extraction, and it continues to
change with time
• The overlying connective tissue also undergoes
changes along with the alveolar bone changes, that
place the soft tissue at risk for pressure-induced
inflammatory changes. This variable tissue support
potential adds complexity to design considerations
while dealing with tooth-tissue-supported prosthesis

• This is because unlike the efficient support provided
by the teeth, which results in limited prosthesis
movement, the reaction of the ridge tissue to
functional forces can be highly variable, leading to
variable amounts of prosthesis movements
• Factors relating to the opposing arch tooth position,
the existence and nature of prosthesis support in the
opposing arch, and the potential for establishing a
harmonious occlusion can greatly influence the partial
denture design

• Opposing tooth positions that apply forces outside
the primary support of the prosthesis can introduce
leverage forces that act to dislodge the prosthesis
• Such an effect is variable based on the nature of the
opposing occlusion – natural teeth, complete denture
or removable partial dentures.
• In general, RPDs opposing natural teeth will require
greater support and stabilization over time because of
greater functional load demands.

DIFFERENTIATION BETWEEN TOOTH –
AND TOOTH-TISSUE SUPPORTED
PROSTHESIS
1. DIFFERENCES IN SUPPORT
2. DIFFERENCES IN IMPRESSION REGISTRATION
3. DIFFERENCES IN CLASP DESIGN

DIFFERENCES IN SUPPORT
• Tooth-tissue supported partial denture derives
primary support from the tissue underlying the base
and secondary support from the abutment teeth.
• Length and contour of the ridge influence amount of
available support & stability
• The movement of the base under function also
influences the occlusal efficiency of the partial
denture and also the degree to which the abutment
teeth are subjected to torque and tipping stresses

• Tooth supported partial denture derives all
support from the abutment teeth

IMPRESSION REGISTRATION
REQUIREMENTS:
1. The anatomic form and relationship of the
remaining teeth in the dental arch & surrounding
soft tissue must be recorded accurately so that the
denture will not exert pressure on those structures
beyond their physiologic limits. A type of impression
material that can be removed from undercut areas
without permanent distortion must be employed
E.g., alginate, mercaptan rubber base, silicone
impression materials and poly ethers best suited

2. The supporting form of the soft tissue underlying the
distal extension base should be recorded so that the
firm areas are used as primary stress bearing areas
and the readily displaceable tissues are not
overloaded. An impression material capable of
displacing tissue sufficiently to register the supporting
form of the ridge will fulfill the second requirement
e.g., mouth temperature waxes, rubber base –
supporting form. ZOE paste can be used when only
the extension base is involved in the impression

• No single impression material can satisfactorily
fulfill both the requirements.

DIFFERENCES IN CLASP DESIGN
• TOOTH-SUPPORTED PARTIAL DENTURE :
• It is totally supported by abutment teeth, so it is
retained and stabilized by a clasp at each end of the
each edentulous space
• As this type of prosthesis does not move under
function, the only requirement of such clasps is that
they flex sufficiently during placement and removal of
the denture to pass over the height of contour of the
teeth, in approaching/escaping from an undercut
area.

• In its terminal position, the retentive clasp
should be passive & should not flex except
when engaging the undercut area of the tooth
to resist a vertical dislodging force

Cast retentive arms may
be used for this
purpose. These may be
either of the
circumferential type,
arising from the body of
the clasp and
approaching the
undercut from an
occlusal direction, or of
the bar type, arising
from the base of the
denture and
approaching the
undercut area from the
gingival direction

• TOOTH-TISSUE-SUPPORTED PARTIAL DENTURE:
• Due to the anticipated functional movement of the
distal extension base, the direct retainer adjacent to
the distal extension base must perform still another
function in addition to that of resisting vertical
displacement.
• Because of the lack of tooth support distally, the
denture base will move tissueward under function
proportionate to the displaceability of supporting soft
tissue, the accuracy of the denture base, & the total
occlusal load applied

• Because of this tissueward
movement, those elements
of a clasp that lie in an
undercut area mesial to the
fulcrum for a distal
extension, must be able to
flex sufficiently to dissipate
stresses that otherwise
would be transmitted
directly to the abutment
tooth as leverage

• Only the retentive arm of the circumferential
clasp, should be made of wrought metal.
Reciprocation and stabilization against lateral
and torquing movement must be obtained
through the use of rigid cast elements, which
make up the remainder of the clasp –
COMBINATION CLASP.

Advantages of combination clasp:
• Greater flexibility
• Adjustability
• Minimum tooth contact
• Better esthetics
The amount of stress transmitted to the supporting
edentulous ridge and abutment teeth will depend
upon
• Direction and magnitude of force
• Length of the denture base lever arms
• Quality of resistance
• Design characteristics of the partial denture

CONTROLLING STRESS BY
DESIGN CONSIDERATIONS

• The statement “ no removable partial denture can be
designed or constructed that will not be destructive in
the mouth” can be thoroughly justified if all rotational
forces and other stresses are considered
• At present, there is no way that all forces can be
totally countered or negated. However, long term
clinical observation has proved that a design
philosophy that strives to control these factors within
the physiologic tolerance of the teeth and supporting
structures can be successful

1. DIRECT RETENTION
• The retentive clasp arm is the element of the partial
denture that is responsible for transmitting most of
the destructive forces to the abutment teeth.
• A RPD should always be designed to keep clasp
retention to a minimum yet provide adequate
retention to prevent dislodgement of the denture by
unseating forces

• There are several components of
the denture that can be used to
contribute to the retention of the
prosthesis so that the amount of
retention provided by the clasps
can be reduced.
• Exploiting this retentive potential in
widely separated areas of the
mouth can result in stress on the
abutment teeth being effectively
reduced; the support and stability
of the prosthesis may be enhanced
as well.

• FORCES OF ADHESION AND COHESION:
• To secure the maximum possible retention through
the forces of adhesion and cohesion, the denture
base should cover the maximum area of available
support and must be accurately adapted to the
underlying mucosa.
• Adhesion is the attraction of saliva to the denture and
the tissues, and cohesion is the internal attraction of
the molecules of saliva to each other

• Although it is not possible to develop a complete
peripheral seal around the borders of a partial
denture because of the presence of teeth,
atmospheric pressure may still contribute a slight
amount of retention
• This may be noted especially on a maxillary complete
palatal major connector when an accurate metal
casting is used and the margins of the connector are
beaded. A partial vacuum can occur beneath the
major connector

• FRICTIONAL CONTROL
• The partial denture should be designed so that
guide planes are created on as many teeth as
possible.
• Guide planes are areas on teeth created so
that they are parallel to the path the denture
takes as it is inserted and withdrawn from the
mouth
• The planes may be created on enamel surfaces
of teeth / restorations placed on the teeth

• Frictional contact of the prosthesis against
these parallel surfaces can significantly
contribute to the retention of the denture

• NEUROMUSCULAR CONTROL:
• The innate ability of the patient to control the
action of the tongue, lips and cheeks can be a
major factor in the retention of the denture
• Design and contour of the denture base can
greatly affect the ability of the patient to
control / retain the prosthesis
• Overextensions will contribute to loss of
retention and the abutment teeth bearing the
direct retainers will be overly stressed because
of the denture being constantly dislodged

• A properly contoured borders of a denture
base can aid in retention by permitting patient
to use neuromuscular skills to avoid dislodging
base.

• QUADRILATERAL CONFIGURATION:
• It is indicated most often for class III arches
particularly when there is a modification space
on the opposite side of the arch.
• A retentive clasp should be positioned on each
abutment tooth adjacent to the edentulous
spaces. This results in the denture being
confined within the outline of the four clasps,,
and leverage on the denture is effectively
neutralised.

• For a class III arch where no modification space
exists, the goal should be to place one clasp as
far posterior on the dentulous side as possible
and one as far anterior as space and esthetics
permit. This retains the quadrilateral concept
and is most effective way to control stress

• TRIPOD CONFIGURATION
• Tripod clasping is primarily used in class II
arches. If there is a modification space on the
dentulous side, the teeth anterior and
posterior to the space are clasped to bring
about the tripod configuration.

• If a modification space is not present, one clasp
on the dentulous side of the arch should be
positioned as far posterior as possible, and the
other as far anterior as factors such as
interocclusal space, retentive undercut, and
esthetic considerations will permit.
• By separating the the two abutments on the
tooth supported side as far as possible, the
largest possible area of the denture will be
enclosed in the triangle formed by the
retentive clasps

• This design is not as effective as the
quadrilateral configuration, but is most
effective in neutralizing leverage in the class II
situation

• BILATERAL CONFIGURATION:
• Most of the removable partial dentures fall into the
bilateral distal extension group, or class I.
• Ideally, the single retentive clasp on each side of the
arch should be located near the center of the dental
arch or denture bearing area.
• For practical purposes , however, the terminal
abutment tooth on each side of the arch must be
clasped regardless of where it is positioned

• In bilateral configuration, the
clasps exert little or no
neutralizing effect on the
leverage induced stresses
generated by the denture base.
These stresses should be
controlled by other
means(indirect retainers

CLASP DESIGN
• CIRCUMFERENTIAL CAST CLASP:
• The conventional circumferential cast clasp
originating from the distal occlusal rest on the
terminal abutment tooth and engaging a
mesiobuccal undercut should not be used on a
distal extension RPD.

• The terminal of this clasp reacts to
movement of the denture base
toward the tissue by placing a distal
tipping, or torquing force on the
abutment tooth. This particular
force is the most destructive force a
retentive clasp can exert.
• A reverse circlet clasp, a cast
circumferential clasp that
approaches a distobuccal undercut
from the mesial surface of a
terminal abutment tooth, is
acceptable.

• An occlusal load applied to the denture
base, moves the retentive terminal into a
greater vertical undercut but engages the
mesiodistal height of contour

• VERTICAL PROJECTION /
BAR CLASP
• It is used on the terminal
abutment tooth on a distal
extension partial denture
when the retentive undercut is
located on the distobuccal
surface.

• As the denture base is loaded towards the tissue, the
retentive tip of the T clasp rotates gingivally to release
the stress being transmitted to the abutment teeth
• One school of thought on the philosophy of RPD
design has advocated omitting the distoocclusal rest
from the terminal abutment in favor of a mesial rest
when a bar clasp is used. The belief is that a distal rest
would cause the fulcrum line around which the
denture tends to rotate to be distal to the retentive
clasp terminal

The advantage claimed for moving
the occlusal rest more anteriorly is
that the lever arm is increased,
which causes the force directed
toward the residual ridge to be
more vertical and thus better
tolerated by the ridge
Omitting a rest adjacent to the
edentulous space permits packing
of food between minor connector
of partial denture and tooth

• COMBINATION CLASP:
• When a mesiobuccal undercut exists on an abutment
tooth adjacent to a distal extension edentulous ridge,
the combination clasp can be employed to reduce the
stress transmitted to the abutment
• Wrought alloy wire, by virtue of its cross sectional
shape and internal structure, is more flexible than a
cast clasp. It can flex in any spatial plane, whereas a
cast clasp flexes in the horizontal plane only. The
wrought wire retentive arm has a stress breaking
action that absorbs torsional stress in both vertical
and horizontal plane

SPLINTING OF ABUTMENT TEETH
• Adjacent teeth may be splinted by means of crowns
to control stress transmitted to a weak abutment
tooth. Splinting two or more teeth actually increases
the periodontal ligament attachment area and
distributes the stress over a larger area of support
• Splinting is also indicated when the proposed
abutment tooth has either a tapered / short roots
such that there is not an acceptable amount of
periodontal ligament area present

• Splinting is also indicated if the terminal abutment
tooth on the distal extension side of the arch stands
alone – an edentulous space exists exists both
anterior and posterior to it. Usually seen often in
second premolars. Such a premolar is potentially a
weak abutment because of the rotational forces it
must withstand. Splinting of this tooth to the tooth
anterior to it, usually the canine, should be
accomplished with a fixed partial denture
• Principal advantage - cross arch stabilization

INDIRECT RETENTION :
•
An indirect retainer is a part of the removable
partial denture that helps the direct retainer
prevent displacement of the distal extension
denture by resisting the rotational movement
of the denture around the fulcrum line
established by the occlusal rests.
98

• In class I arch the indirect retention must always be
used but is not critical in case of class II.
• The indirect retainer or retainers must be positioned
as far anterior to the fulcrum line as possible.
• If a modification space exists on the tooth
supported side, abutment teeth on both sides of the
space should be selected.
99

• For class III arch, indirect retention is not
ordinarily required, because there is no distal
extension denture base to create a lever arm.
• The consideration for the class IV arch is the
reverse of that for class I and class II arches. The
lever arm is anterior to the fulcrum line so the
indirect retainer must be located as far
posteriorly as possible.
100

OCCLUSION
• A Smoothly functioning occlusion that is in
harmony with the movements of both the
TMJs and the neuromusculature will minimize
the stress transmitted to the abutment teeth
and residual ridge.
• The contacts of the remaining natural teeth
must be same when the removable partial
denture is in the mouth as when the prosthesis
is not in place

DENTURE BASE
• should cover as extensive an area of
supporting tissue as possible – stress is
distributed over a large area
• The distal extension denture base must always
extend on to the retromolar pad area of the
mandible and cover the entire tuberosity in the
maxilla

• Avoid overextensions as it interferences with the
functional movements of the surrounding tissues and
transmit significant stresses to the remaining teeth
• The more accurate the adaptation of the denture
base to the residual ridge, the better will be the
retention, in part because of the forces of adhesion
and cohesion

The type of impressions used to record the
mucoperiosteum of the ridge will influence the
amount of stress the residual ridge can effectively
absorb

MAJOR CONNECTOR
• In the mandibular arch,
the lingual plate major
connector that is
properly supported by
rests can aid in the
distribution of
functional stresses to
the remaining teeth. It is
particularly effective in
supporting periodontally
weakened anterior
teeth

• In the maxillary arch,
the use of broad palatal
major connector that
contacts several of the
remaining natural teeth
can distribute stress
over a large area. The
major connector must
be rigid and must
receive vertical support
through rests from
several teeth

MINOR CONNECTORS
• The most intimate tooth- to- partial
denture contact takes place between
the minor connector joining the clasp
assembly to the major connector and
the guiding planes on the abutment
tooth surface.
• This close contact serves two
purpose

1. It offers horizontal stability to the partial denture
against lateral forces on the prosthesis.
2. Provides a distinct path of insertion and removal
thereby helping in prosthesis retention.

RESTS
Properly prepared rests seats help control stress by
directing forces transmitted to abutment teeth down
along the long axis of those teeth.
The pdl is capable of withstanding vertical forces of far
greater magnitude than horizontal/ torsional forces.
During function, these forces
average 196 Newtons (44lb)
and during parafunction,
295 Newtons(66lb).

• The floor of the rest seat preparation must
form an angle of 900 with the perpendicular
line dropped down the long axis of the tooth –
permits the rest to grasp the tooth securely
and prevents its migration

• The number of abutment teeth influences the
amount of force each tooth must absorb. The
more teeth that bear rest seats, the less will be
the stress placed on each individual tooth

PHILOSOPHY OF DESIGN
The variations in the concept of design are
multitudinous. However, there are three
basic underlying approaches to distributing
the forces acting on the partial denture
between the soft tissue and teeth.
1. Stress equalisation
2. Physiologic basing
3. Broad stress distribution

STRESS EQUALISATION
• Also referred to as stress directing approach
• This concept emphasises that the resiliency of
the tooth secured by the periodontal ligament
in an apical direction is considerably lesser
than that of the greater resiliency and
displaceability of the mucosa covering the
edentulous ridge

• This school of thought believes that the rigid
connection between the denture bases and the direct
retainer on the abutment teeth is damaging and that
some type of stress director or stress equaliser is
essential to protect the vulnerable abutment teeth
• Eg., a hinge device interposed between the minor
connector of the abutment tooth and the denture
base. The hinge is designed to permit vertical
movement of the denture base as occlusal forces are
applied to the artificial teeth. The amount of vertical
movement permitted is usually the estimated
thickness of the mucosa covering the ridge

ADVANTAGES
• The stress director design usually calls for minimal
direct retention, because the denture base operates
more independently than in a conventional denture
• Internal attachments for retention of the stress-
broken prosthesis are widely used.
Advocates of this theory, stress the importance of
stress equaliser in case of class I and class II partial
dentures because of the positive lock on the
abutment tooth caused by the internal attachment.
Thus, the stress director eliminates the tipping strain
on the tooth, thereby preventing bone resorption
around the tooth

• ACTION OF STRESS EQUALISER
• Resiliency of the resiliency of
stress equaliser + periodontal ligament
= resiliency of mucosa
• Thereby, the forces are equally distributed
between the teeth and soft tissue

DISADVANTAGES
• Fragile
• Construction – complex + costly
• Need for constant maintenance
• Difficult/impossible to repair
• Lacks the ability to prevent damaging lateral
stresses from occuring on the edentulous
ridge, resulting in the rapid resorption of bone
and settling of the denture

• If sufficient thickness of metal in the hinge region is
used to prevent lateral movement, the prosthesis
becomes heavy, bulky and annoying to the patient.
Of the three schools of thought of partial denture
design, the stress equalising school has the least
advocates.

PHYSIOLOGIC BASING
• This school denies the use of stress directors to
equalise the disparity of vertical movement between
the tooth and mucosa. They believe that equalisation
can best be accomplished by some form of
physiologic basing/lining of the denture base.
• Physiologic basing is produced either by
displacing/depressing the ridge mucosa during the
impression making procedure or by relining the
denture base after its construction

• The reason for displacing the mucosa during the
impression procedure is to record the soft tissue in its
functioning, and not anatomic form.
• The rationale – if the tissue is recorded in its
functioning form when occlusal forces take place on
the denture, the denture base, formed over the
displaced tissue, will adapt more readily to the
depressed tissue and will be able to withstand the
forces that are generated

• The artificial teeth of a RPD constructed from a tissue
displacing impression will be positioned above the
plane of occlusion when the denture is in the mouth
and not functioning
• To permit vertical movement of the partial denture
from the rest position to the functioning position, the
direct retainers/retentive clasps must be designed
with minimum retention and the no. of direct
retainers must be limited

• The occlusal rests and direct retainers will also
be slightly unseated at rest and will be
completely seated only when the mucosa
beneath the denture base is displaced to its
functional form.

ADVANTAGES
• Intermittent pressure against the mucosa caused the
movement of the denture base as occlusal loads are
applied and removed has a stimulating effect on the
underlying bone and soft tissue– this stimulation
reduces tissue changes as well as the necessity of
relining/rebasing to compensate for tissue change as
is required for most distal extension partial dentures.

• Simplicity of design and
construction because of
minimal retention
requirements results in
light weight prosthesis
needing minimum
maintenance and repair

• Minimal direct retention: the looseness of the
clasps on the abutment tooth reduces the
functional forces transmitted to the tooth –
preserving the abutment teeth

DISADVANTAGES
• Denture is not stabilised against lateral forces
because of the minimum number and flexibility of
the direct retainers. The residual ridge receives a
greater proportional amount of the forces that are
transmitted by the denture
• As the artificial teeth are always slightly above the
occlusal plane when the denture is not in function,
there will always be slightly premature contacts
between the opposing teeth and the denture teeth
when the mouth is closed

• It is difficult to produce effective indirect retention
because of the vertical movement of the denture and
the minimal retention of the direct retainer. By the
time the indirect retainer engages a rest seat to
prevent the denture base from being dislodged, a
direct retainer will have lost contact with the
abutment teeth

BROAD STRESS DISTRIBUTION
• Advocates of this school of partial denture design
believe that excessive trauma to the remaining teeth
and residual ridge can be prevented by distributing
the forces of occlusion over as many teeth as possible
and as much soft tissue as possible.
• This is accomplished by the use of additional rests,
indirect retainers, clasps and broad coverage denture
bases.

Maximum coverage of teeth and soft tissues – distribution
of forces over as wide an area as possible

ADVANTAGES
• The forces of occlusion are reduced on any tooth or
area of the ridge because all the teeth and entire
available ridge collectively bear the load.
• Multiple tooth contacts by direct retainers, additional
rests, and minor connectors cause distribution of
lateral forces over as many teeth as possible

• Multiple clasps also aid in lateral stability – for the
prosthesis as well as the periodontally compromised
teeth. This constitutes a form of removable splinting
which can be useful in instances where fixed splinting
is not indicated
• The prosthesis is easier to fabricate and less
expensive

• No flexible parts – so there is less danger of distorting
the denture
• Less subject to breakage
• Indirect retainers and other rigid components
prevent rotational movements of the denture and
provide excellent horizontal stabilization.
• Due to increased stability and decreased movement,
it does not require frequent relining

DISADVANTAGES
• Greater amount of tooth and soft tissue coverage
results in increased bulk – less patient comfort, less
patient acceptance
• Constant monitoring for dental caries
• Meticulous oral hygiene

• During design, simplicity is of prime importance, but
not at the expense mechanical and biologic standards
that are necessary for maintenance of patient’s health
• A knowledge of the components of the partial
denture and functions of the individual parts is
absolutely necessary to make meaningful decisions
for any given situation.

COLOR CODING
• A color coding system for various parts of the
removable partial denture should be included on the
diagnostic casts to help prevent confusion on the part
of the dental technician or anyone trying to
understand the design being proposed
• A well designed diagnostic cast also serves as a
blueprint for the dentist during the mouth
preparation appointment

• At present there is no universally accepted
color coding system. Any system agreed to and
understood by the dental lab and the dentist is
acceptable
• COLORS USED:
• Red crayons
• Blue crayons
• Brown crayons
• Black lead pencil – 2H or 3H

• The brown crayon pencil – to outline metallic portion
of the partial denture
• Blue – acrylic resin portion
• Red – to indicate areas on the teeth that will be
prepared, relieved or contoured.
• Solid red – rest seats
• Red – tooth surfaces that are to be recontoured

• Black pencil and carbon marker in the surveyor are
used to denote survey lines, soft tissue undercuts, &
other information to be included, such as the type of
tooth replacement or the use of wrought wire for
retentive clasps

1. EXAMINATION OF THE OCCLUDED
DIAGNOSTIC CASTS

• Indicate the proposed rest areas by a short
vertical line on the cast below the tooth with
the black pencil – in event of any change in rest
seat location, corrections will not have to be
made on the teeth

• Indicate by
outlining in red any
cuspal relief that
will be needed to
provide adequate
clearance for rest
spaces.

• Examine the lingual aspect of the occluded casts for
adequate space for cingulum rests, indirect retainers,
and so on. Using the black pencil from the rear
surface of the casts, draw a line on the lingual
surfaces of the maxillary anterior teeth using the
incisal edges of the mandibular teeth as a guide.
• This line shows the incisal limit of proposed metal
extension [ rests/lingual plating] onto those teeth

2. Indicate with a pencil, using the following symbols,
the type of tooth replacement desired
• T – tube tooth
• F – facing
• M - metal pontic
• RAP – reinforced acyrlic pontic
• NO SYMBOL – denture teeth on denture base
• Place these symbols on the soft tissue portion of the
cast, adjacent to the edentulous area. One symbol
should be used for each tooth replacement

• Facings- when
strength is greatest
requirement, limited
esthetics
• Tube teeth – little
resorption of ridge,
very esthetic
• RAP - little resorption
of ridge, slightly
stronger than tube
teeth
• Acrylic resin teeth –
resorbed ridges

3. Place the cast on the cast holder at a horizontal tilt.

RETENTIVE UNDERCUTS
Examine the teeth to be clasped
for favorable retentive undercuts.

ESTHETICS
Examine the anterior edentulous
areas for esthetic considerations.

GUIDING PLANES
Examine the proximal and
lingual tooth surfaces
for guiding planes.

SOFT TISSUE UNDERCUTS
Beware of soft tissue undercuts that may interfere with
the placement of the partial denture.

4. Tripoding the cast
To tripod the cast, the tip
of the carbon marker must
contact the cast at 3 widely
separated points while the
cast remains at a fixed tilt
and the marker remains at
a constant height. The
marker scribes a 4-to -5
mm horizontal line at the 3
selected points

5. Place the carbon marker in the vertical arm of
the surveyor and scribe the survey line on the
teeth that will be contacted by the partial
denture

• Survey lines may be
transferrred to the teeth
and other structures on the
cast by releasing the vertical
arm of the surveyor and
rotating the cast while the
side of the carbon marker
remains in contact with the
tooth
• Everything gingival to the
survey line will be undercut
to the path of insertion

• The survey line is also
transferred to soft tissue
areas that will be
contacted by the partial
denture
• No rigid component of
the prosthesis can lie
below the survey line

6. Replace the carbon marker with the appropriate
undercut gauge
• For most clasps of chrome cobalt alloy, a 0.010 inch
undercut is adequate.
• for wrought wire retentive clasps, 0.02 inch is usually
indicated
• Place the gauge on the desired retentive undercut
area, so that the head and shank of the gauge touch
the tooth simultaneously
• With a red pencil, mark the spot that the head
touches the tooth. This mark represents the gingival
edge of the clasp tip in the desired retentive undercut

• The 0.01 – inch undercut
gauge is used to position the
lower border of the tip of
the retentive clasp
• The shank contacts the
molar at the survey line as
the lid of the gauge contacts
the tooth. This point should
be marked with the red
pencil

7. With a red pencil draw the extent of the rest areas to
be prepared in the mouth
The full extent of the rest seat should now be colored solid red.
It has to be drawn in actual size so that the effect of the rest seat
on the surrounding and opposing structures can be accurately
forecast

8.Using a red pencil, outline tooth surfaces that will require
recontouring to produce the desired results
• Place evenly spaced diagonal lines to ensure
that these areas are highly visible.
• Areas of soft tissue relief should be outlined in
red and accompanied by the word relief.

• 9. Using a blue pencil, outline the exact position of
each acrylic resin denture base

10. With a brown pencil outline the frame work
design to harmonise and join the major
connectors, rest areas, indirect retainers,
minor connectors, denture bases and
replacement teeth. Use a carbon marker to
outline soft tissue undercuts that will influence
the design

• Maximum support from
the hard palate must be
the goal
• The anterior extent of
the major connector is
scalloped to simulate
the necks of the tube
teeth

• Lingual bar mandibular
major connector –
superior margin should
not be closer than 3 mm
to the gingival margin of
the teeth

• The minor connector is
added to the design –
open latticework
• It should cover the
tuberosity

11. With a brown pencil, draw the clasp arms to the
actual shape, size and location desired.
If wrought wire clasps are to be used, place the symbol
WW on the soft tissue below the tooth

• The size, position, and
contour of the clasps should
be drawn accurately so that
possible interferences with
opposing arch can be
detected
• Circumferential clasp - only
terminal third of clasp arm
below survey line
• Modified T clasp – approach
arm is positioned superior to
soft tissue undercut

• Retentive clasp should be
smoothly tapered and
should be curved as it
crosses the tooth surface – it
should never run straight
across the tooth
• Retentive clasps should be
kept as low on the crown of
the tooth as the survey line
permits, preferably in the
gingival third

• The final components to be
added are the reciprocal
clasp arms. The arms should
not be tapered as flexibility
should be avoided
• It should always be
positioned above the survey
line, at the junction of
gingival and middle thirds of
the crown
• If survey line is too high to
permit this, the enamel
surface must be
recontoured to lower the
survey line

11. The design should now be complete. Re-
examine for accuracy and clarity

CLASS I AND II
• DIRECT RETENTION:
• Retention should NOT be considered the prime
objective of design
• Main objective: restoration of function and
appearance and maintenance of comfort, with great
emphasis on preservation of health and integrity of all
the oral structures that remain

• Close adaptation and proper contour of an
adequately extended denture base and
accurate fit of the framework against multiple,
properly prepared guide planes should be used
to help the retentive clasp arms retain the
prosthesis

• CLASPS
• Clasps that will accomplish the design objectives
should be employed
• Should have good stabilizing qualities, remain passive
until activated by functional stress, and accommodate
a minor amount of movement of the base without
transmitting torque to the abutment
• Should be strategically positioned in the arch to
achieve greatest possible control of stress

• A class I prosthesis usually requires only two
retentive clasp arms : one on each terminal
tooth
- If distobuccal undercut is present, vertical
projection retentive clasp preferred
- If mesiobuccal undercut is present a wrought
wire clasp is indicated
- Reciprocal/ bracing arm must be rigid. This
component can be replaced by lingual plating

• A class II prosthesis should usually have three
retentive clasps arms
- Distal extension side – same as class I prosthesis
- Tooth supported side should have 2 retentive clasps
arms – one as far as posterior and one as far anterior
as tooth contours and esthetics permit
- If modification space exists, its convenient to clasp a
tooth anterior and a tooth posterior to the
edentulous space
- The type of clasp & position of the retentive undercut
can be selected for convenience
- Rigidity is required for all bracing arms. Lingual plating
may be substituted

• RESTS
• Teeth selected for rest preparation should
provide maximum possible support for the
prosthesis
• Rest seats should be prepared so that stress
will be directed along the long axis of the teeth
• Rests should be placed next to the edentulous
space with few exceptions

• INDIRECT RETENTION
• Indirect retention should be employed to neutralize
the unseating forces
- It should be located as far anterior to the fulcrum line
as possible
- Two indirect retainers should generally be used in a
class I design, whereas one placed on the side
opposite the distal extension base may be adequate
in a class II

• The indirect retainers should be positioned in teeth
prepared with positive rest seats that will direct
forces along the long axis of the tooth.
• Lingual plating can be used to extend the
effectiveness of indirect retention to several teeth. It
must always be supported by positive rest seats

• MAJOR CONNECTOR
• The simplest connector that will accomplish the
objectives should be selected
- it must be rigid in nature
- must not impinge on gingival tissue

• Support from hard palate should be used in the
design of maxillary major connector when it would be
beneficial
• Extension on to the lingual surfaces of the teeth may
be employed to increase rigidity, distribute lateral
stresses, improve indirect retention, or eliminate
potential food impaction areas. Lingual plating should
always be supported by adequate rest seats

• MINOR CONNECTORS
• It must be rigid
• Should be positioned to enhance comfort,
cleanliness, and the placement of artificial
teeth

• OCCLUSION
• Centric occlusion and centric relation should coincide
• A harmonious occlusion should be established with no
interceptive contacts and with all eccentric
movements dictated by or in harmony with, the
remaining natural teeth
• Artificial teeth should be selected and positioned to
minimize stresses produced by the prosthesis

• Smaller and/or fewer teeth, and teeth that are
narrower buccolingually may be selected
• For mechanical advantage, teeth should be
positioned over the crest of the mandibular
ridge whenever possible
• Teeth should be modified if necessary to
produce sharp cutting edges and ample
escapeways

• DENTURE BASE
• The base should be designed with broad coverage so
that the occlusal stresses can be distributed over as
wide an area of support as possible
• The extension of the borders must not interfere with
functional movements of the surrounding tissues
• A selective pressure impression should record the
residual ridge in its functional form
• The polished surfaces should be contoured to enable
the patient to exercise maximum neuromuscular
control

MANDIBULAR CLASS I
• SYMMETRICAL

MAXILLARY CLASS I
• WITHOUT MODIFICATION SPACE

MANDIBULAR CLASS II
• WITH NO MODIFICATION

• WITH POSTERIOR MODIFICATION

• WITH ANTERIOR MODIFICATION

• WITH ANTERIOR AND POSTERIOR MODIFICATION

MAXILLARY CLASS II

• WITH ANTERIOR AND POSTERIOR
MODIFICATION

CLASS III
• DIRECT RETENTION
• Retention can be achieved with much less
potential harmful effect on the abutment teeth
than with class I or II arch
• The position of the retentive undercut on
abutment teeth is not critical

• CLASPS
• The quadrilateral positioning of the direct
retainer is ideal
• The type of clasp selected is not critical
• Tooth and tissue contours and esthetics
should be considered, and the simplest clasp
possible should be selected
• If restorations are required to correct the tooth
contours, the wax patterns must be shaped
with the surveyor
• Bracing arms must be rigid

• RESTS
• Rest seats should be prepared next to the
edentulous space when possible
• Rests should be used to support the major
connector and lingual plating

• INDIRECT RETENTION
• Indirect retention is usually not required

• MAJOR AND MINOR CONNECTORS
• They must be rigid and meet the same
requirements as for a class I or II design
• OCCLUSION
• The requirements for occlusion are the same as
for a class I or II design

• DENTURE BASE
• A functional type of impression is not needed
• The extent of coverage of the residual ridge
areas should be determined by appearance,
comfort, and the avoidance of food impaction
areas

MANDIBULAR

MAXILLARY
• ANTERIOR EDENTULOUS SEGMENTS

• POSTERIOR EDENTULOUS SEGMENTS

• BOTH ANTERIOR AND POSTERIOR
EDENTULOUS SEGEMENTS

CLASS IV
• The movements of this type of removable partial
denture and the resulting stresses transmitted to the
abutment teeth are unlike the pattern seen in any
other type of prosthesis
• The esthetic arrangement of the anterior replacement
teeth may necessitate their placement anterior to the
crest of the alveolar ridge, resulting in potential tilting
leverage

• Every effort should be made in order to minimize
these stresses. Some of the possibilities –
• As much of the labial alveolar process should be
preserved as possible
• A central incisor or other tooth should be retained to
serve as an intermediate abutment or as an
overdenture abutment
• A critical evaluation of each remaining tooth in the
arch should be made with the intent of retaining as
many teeth as possible

• Strategic clasp position should be used. The
quadrilateral configuration with the anterior clasps
placed as anterior and the posterior clasps placed as
far posterior as possible, would be ideal
• The major connector should be rigid, and broad
palatal coverage should be used in the maxillary arch

• Indirect retention should be as far posterior to the
fulcrum line as possible
• An ideal quadrilateral configuration of clasping may
preclude the need for an additional indirect retainer
• A functional type of impression may be indicated if
the edentulous area is extensive

• Frechette AR in 1951 studied partial denture
planning with special reference to stress
distribution and concluded that
• Wide distribution of vertical stress is obtained
by use of rigid connector with broad saddles
and properly applied rests
• The rest seat should be spoon shaped and at
right angles to the long axis of the tooth
• Clasp arm should embrace more than 1800 of
the tooth circumference and remain passive
unless actively retaining the denture

• Jordan LG in 1952 studied designing removable
partial dentures with external attachment
[clasps] and stated that vertical, lateral and
anteroposterior occlusal forces can be well
distributed by proper occlusal rest seats and
occlusal rest, use of rigid retainer connector,
proper clasp arm design, use of rigid base
connectors

• Osborne J, Lammie GA in 1954 presented the
treatment of free end saddle and advocated
use of
• Narrow occlusal table for reduction of vertical
load
• Use of a stress breaker by distributing load
between teeth and alveolus
• Distributing load widely over more than one
abutment tooth on each side

• Henderson D in 1967 studied force distribution
with removable partial dentures and concluded
that
• Use of rigid major connector linking abutment
teeth on each side of the arch was an effective
means of decreasing the force occuring to
abutment teeth nearest the site of application
of non-vertical force
• Abutment of a removable partial denture
positioned farthest from the site of application
of force to the dentures participate the least in
resisting the force

• Cecconi BT in 1974 studied effect of rest design
on transmission of forces to abutment teeth
and concluded that
• Precision rests and deep rests affect abutment
tooth movement in a similar manner
• Rests with gingival seats at maximum depth in
abutment teeth can significantly decrease
abutment tooth movement
• Bilateral loading of a RPD causes significantly
less abutment tooth movement than does
unilateral loading

• Krol AJ in 1973 studied clasp design for
extension base removable partial denture and
advocated RPI clasp because it minimises tooth
coverage and reduces stress on the abutment
tooth

• Green LK, Hondrum SO in 2003 studied effect
of design modification on the torsional and
compressive rigidity of U shaped palatal major
connectors and concluded that doubling the
thickness of the anterior strap of a U shaped
maxillary major connector improved the
rigidity of the framework to torsional loads

• Authorities in the field of removable partial
denture design differ in their approach in
developing the design of each individual
prosthesis.
• Any of the above mentioned philosophies can
be successful if applied to the correct partially
edentulous situation and that all will fail if used
under incorrect circumstances

• There is, however complete agreement that
the correct design incorporates proper use and
application of mechanical and biologic
principles.

REFERENCES
• Alan B Carr, Glen P, David T Brown. Mc
Cracken’s Removable Partial Prosthodontics.
11th edition
• Kenneth Stewart , Kenneth Rudd. Clinical
Removable Partial Prosthodontics. Second
edition
• Russell Stratton, Frank Wiebelt. An Atlas Of
Removable Partial Denture Design

• Frechette AR. Partial denture planning with
special reference to stress distribution. J
Prosthet. Dent. 1:710-24;1951
• Jordan LG. Designing removable partial
dentures with external attachments.
JPD.2:716-22;1952
• Osborne J, Lammie GA. The bilateral free end
saddle lower denture. JPD.4:640-53;1953

• Henderson D, Steward TE. Design and force
distribution with removable partial dentures.
JPD 17:350-64;1967
• Cecconi BT. Effect of rest design on
transmission of forces to abutment teeth.
JPD.32:141-51;1974
• Krol AJ. RPI [ rest, proximal plate, I-bar] clasp
retainer and its modification. Dent Clin North
Am. 17[4]:631-49;1973

• Green LK, Hondrum SO. The effect of design
modifications on the torsional and compressive
rigidity of U shaped palatal major connector.
JPD.131-5;2003

Designing of rpd

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